"Those with blood on their blades don't cross the Lower Yangtze." No So-ha, the sole heir to the reputedly invincible Nine Flow Swordsmanship, lives a low-profile life with three sources of income: fishing, ferrying customers across the Lower Yangtze, and as a contract hitman for victims of injustice. Despite trying to stay away from the conflicts among martial arts factions, he finds himself taking up the most dangerous job of all: escorting to safety in Korea a girl who holds the missing part of the Sun Gun Gyung, a 1,500-year-old medical treatise written for Emperor Qin Shi Huang that is the key to achieving immortality. A Korean xianxia webtoon about a blade-for-hire's adventure in Yuan China.